From 6a5f0e2f9352accf857f683518bd3cc6ef6ae6c6 Mon Sep 17 00:00:00 2001 From: Alexandre Belloni Date: Fri, 3 Feb 2017 23:53:16 +0100 Subject: [PATCH] tty/serial: atmel: ensure state is restored after suspending When going to suspend, the UART registers may be lost because the power to VDDcore is cut. This is not an issue in the normal case but when no_console_suspend is used, we need to restore the registers in order to get a functional console. Signed-off-by: Alexandre Belloni Reviewed-by: Nicolas Ferre Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/atmel_serial.c | 44 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c index fabbe76..8d2cec0 100644 --- a/drivers/tty/serial/atmel_serial.c +++ b/drivers/tty/serial/atmel_serial.c @@ -175,6 +175,17 @@ struct atmel_uart_port { unsigned int pending_status; spinlock_t lock_suspended; + struct { + u32 cr; + u32 mr; + u32 imr; + u32 brgr; + u32 rtor; + u32 ttgr; + u32 fmr; + u32 fimr; + } cache; + int (*prepare_rx)(struct uart_port *port); int (*prepare_tx)(struct uart_port *port); void (*schedule_rx)(struct uart_port *port); @@ -2659,6 +2670,20 @@ static int atmel_serial_suspend(struct platform_device *pdev, cpu_relax(); } + if (atmel_is_console_port(port) && !console_suspend_enabled) { + /* Cache register values as we won't get a full shutdown/startup + * cycle + */ + atmel_port->cache.mr = atmel_uart_readl(port, ATMEL_US_MR); + atmel_port->cache.imr = atmel_uart_readl(port, ATMEL_US_IMR); + atmel_port->cache.brgr = atmel_uart_readl(port, ATMEL_US_BRGR); + atmel_port->cache.rtor = atmel_uart_readl(port, + atmel_port->rtor); + atmel_port->cache.ttgr = atmel_uart_readl(port, ATMEL_US_TTGR); + atmel_port->cache.fmr = atmel_uart_readl(port, ATMEL_US_FMR); + atmel_port->cache.fimr = atmel_uart_readl(port, ATMEL_US_FIMR); + } + /* we can not wake up if we're running on slow clock */ atmel_port->may_wakeup = device_may_wakeup(&pdev->dev); if (atmel_serial_clk_will_stop()) { @@ -2681,6 +2706,25 @@ static int atmel_serial_resume(struct platform_device *pdev) struct atmel_uart_port *atmel_port = to_atmel_uart_port(port); unsigned long flags; + if (atmel_is_console_port(port) && !console_suspend_enabled) { + atmel_uart_writel(port, ATMEL_US_MR, atmel_port->cache.mr); + atmel_uart_writel(port, ATMEL_US_IER, atmel_port->cache.imr); + atmel_uart_writel(port, ATMEL_US_BRGR, atmel_port->cache.brgr); + atmel_uart_writel(port, atmel_port->rtor, + atmel_port->cache.rtor); + atmel_uart_writel(port, ATMEL_US_TTGR, atmel_port->cache.ttgr); + + if (atmel_port->fifo_size) { + atmel_uart_writel(port, ATMEL_US_CR, ATMEL_US_FIFOEN | + ATMEL_US_RXFCLR | ATMEL_US_TXFLCLR); + atmel_uart_writel(port, ATMEL_US_FMR, + atmel_port->cache.fmr); + atmel_uart_writel(port, ATMEL_US_FIER, + atmel_port->cache.fimr); + } + atmel_start_rx(port); + } + spin_lock_irqsave(&atmel_port->lock_suspended, flags); if (atmel_port->pending) { atmel_handle_receive(port, atmel_port->pending); -- 2.7.4